I’m Xiaoyu Yan, a data engineer focused on production data systems and data platform reliability.

Before data engineering, I spent years around biology, food science and engineering, epidemiology, and biostatistics. That background still shapes how I think about systems, evidence, and reliability.

This site collects generalized field notes from engineering work and graduate study: production debugging, migration work, runtime behavior, data contracts, Spark execution boundaries, access-control workflows, and information infrastructure.